1. Field of the Invention
This invention relates in general to excavation and load retrieval equipment, and it deals more particularly with a clamshell type bucket of the kind used for deep-sea mining operations and mineral retrieval. It is specifically directed to a single line deep-sea bucket which may be easily operated in remote depths in excavating minerals from the ocean floor, wherein there is provided such a bucket which may be easily retrieved when the same becomes engaged or locked accidentally on some obstruction in the operating area.
Heretofore, deep-sea clamshell type buckets which are operated from crane ships or barges have been of the multiple tether line type, requiring lines to be strung to the bucket at different angles in order to prevent entangling or the single line type adapted for removing material at great depths which have been provided with messenger means for closing the bucket at initial operation, but had no means for opening the bucket once it had locked for emergency situations.
It is well-known that, with the dwindling mineral resources of this country, mining of the ocean floor has become commonplace. As better exploratory methods are found, more areas on the ocean floor will be revealed where valuable mineral resources may easily be recovered for use in the domestic market without seeking these minerals abroad. It is well-known that present operations in the most favorable mineral locations are at depths ranging in hundreds to thousands of feet.
With such great distances between the tender ships or barges and the operating sea bucket or clamshell, a familiar hazard has become the current of the ocean itself in snarling the many tether lines which are necessary for the purpose of opening, closing and retrieving the deep-sea bucket. Hence, it is very desirable from this standpoint to eliminate as many tether lines running to the surface as possible, for often as the bucket descends it is caused by the current to move at great distances laterally away from its tender and revolve in motion while descending. Since there is no way in which one can observe the condition of these tender lines when they become entangled there is no alternative to bringing the bucket back to the surface, at great loss of time, and some expense, for the purpose of preparing it to descend again to do its job.
The few single line buckets which have been provided have been directed solely to the proposition of opening the bucket in its initial stages in order that it might receive its cargo or in closing the bucket in one operation in order that it might be locked onto its cargo for removal to the surface.
Another hazard, however, is encountered in the possible locking of a bucket onto an outcropping of rock or some other sunken marine object. When this occurs, and there is no means to disengage the bucket, the entire apparatus is lost since it must be cut loose from its tender without being retrieved. The present single line buckets do not provide for this hazard and the present multiple tether line buckets are no practicable in operation at great ocean depths in swirling currents. Hence there is need for a bucket of the single line type which will also be operational to release itself when it locks by accident upon a sunken object.
2. Discussion of Prior Art
After competent search, no existing devices of the type disclosed in the present invention were found, there being seven references which were considered, but which do not appear to conflict with the present invention or anticipate either the apparatus or the objects and purposes for which it was designed. The prior art discloses the following U.S. patents:
T. J. Wetherbee, U.S. Pat. No. 3,762,078
B. L. Crump, U.S. Pat. No. 3,949,497
F. Caoli, U.S. Pat. No. 2,242,940
J. Baird, Jr., U.S. Pat. No. 3,036,393
E. Woolley, U.S. Pat. No. 1,477,679
P. DeBosredon, 3,357,506
C. A. Morris, 400,936
Wetherbee discloses a Benthic dredge construction adapted for taking samples from the bottom of a body of water. In this patent, the clamshell bucket is maintained in the normally "open" position by means of the cables 34 and 35 having engaging loops over the retaining legs 30 of the members 29 which are secured to the operating bar 28. The spring 32 maintains the bar 28 and the members 29 biased away from the bucket such that the legs 30 project from the bracket 26 to receive the loops of the cables. When the bucket is positioned on the floor of the ocean, a messenger is sent down the cable 53 to strike the operating bar 28, moving the projecting members 30 through the bracket 26 to release the cables 34 and 35 and allow the bucket to snap into the closed position gathering a sample. There is no part of this patent which suggests any portion of the present invention, it being for a different purpose with different structure normally maintained in an exactly opposed position diametrically opposite to the present invention.
Crump discloses a releasing latch apparatus for a Benthic dredge which is an improvement over the patent to Wetherbee. It again deals with a clamshell type of bucket for deep-sea operations wherein the lower doors of the bucket are normally maintained in the open position by means of the cables 9 and 10 which are hooked over the latch pins 27. The clamshell closures 2 and 3 remain normally biased toward the closed position by means of a torsion spring 4. The upper ends of the cables 9 and 10 have loops which pass over the latch pins 27 which project through openings 25 in the elongate body cross member 15. A compression spring 34 is adapted to seat against one end of the plunger 23 and rest upon the web 8 of the bail 7, thereby holding the plunger in such position as to maintain the pins 27 projecting from the elongate body 15. In such position the pins hold the loops of the cable 9 and maintain the clamshell closures 2 and 3 in the open position. It can plainly be seen from both of the preceding patents which have been referred to that neither of them operate linkage to achieve the same purpose as that of the invention of the applicant. The messenger which is used in both instances is used to actuate mechanism which will allow the doors which are normally biased to the closed position to be released so that they may spring into the closed position to pick a sample from the bottom of the ocean floor. There is no suggestion by either of these patents of the structure or apparatus as disclosed in this case by the applicant.
Caoli discloses an automatic clamshell bucket which has a double linkage system which allows the bucket to be lowered in such manner that the clamshell closures 10 are in the open position. In this position, telescoping shaft 19 is such that it is in an upward position. When the tension is relieved on the cable 24 the shaft 19 is spring biased in such manner that it moves downwardly such that the lower end of the head 20 and shoulder 21 are caught under the projection 30 of the catch 29. When this engages the catch 29, an upward movement on the cable 24 pulls the entire pivotal connection at 12 upwardly forcing the linkage arms 17 downwardly in such manner as to close the closures 10. Nothing in this patent is used for the purpose of an emergency release of the doors by means of the structure disclosed by the applicant. Nor is there any suggestion in this structure of the same structure as the applicant's. Indeed, this is the type of structure which the applicant seeks to avoid since it entails the use of a separate line 39 in order to release or lock the closures 10 in the appropriate position.
The patent to Baird essentially shows a means for absorbing the shock when the clamshells open after being dropped. In this invention, there is a hoisting line 21 and also a release line 61 to release the mechanism and open the bucket. While the invention is referred to as a single hoist bucket, this is by reason of the fact that the bucket is lowered into position for operation by means of a single line, but in order to release the bucket the extra line 61 must be operated by the same operator to release the hook 34 which will allow the bucket to open. The shock absorbing mechanism is the principle object of the invention and therefore this structure does not in any way suggest the emergency opening feature as shown by the applicant in the instant invention, nor does this invention show the structure for operating a bucket which is shown in the present invention. There is nothing which would suggest the structure of the applicant.
The patent to DeBosredon shows a drilling bucket which is adapted to be operated in a shaft by hydraulic means. This bucket is so adapted that there is a casing which expands to impinge against the side of the hole in which the drilling is taking place in such manner as to prevent a vertical movement of the bucket while the clamshell is open. This type of arrangement does not in any way suggest the frame apparatus of the applicant or the release apparatus of the applicant in the structure which is disclosed by this patent.
Woolley shows a dredging bucket in which it might appear that there would be a similarity to the present device of the applicant because of the fact that tongs are used and a tongue is used in connection therewith. The application and interchange of use of these elements is entirely different, however, from that of the present invention. The upward pull on the hoisting cable 10 and the hoisting cable 6 results in a continuous operation of closing the bucket once it has been loaded such that it will not again release while beneath the surface of the water on the bottom of the ocean floor. These parts are not combined to enable one to release the bucket while tension is placed upon the hoisting cables to pull the bucket up to the surface. Therefore, the bucket might be engaged or hooked upon some outcropping of rock and there would be no means for disengaging the same as in the present invention. There is no similarity between this patent and the present invention and there is no suggestion of the present structure.
The patent to Morris shows a dredging bucket in which the structure is designed to prevent the shock of the drawing of the bucket toward the surface or the lowering of the bucket into the water by means of a spring assembly which takes up the concussion between the conical flange and the latches as the bucket is lowered to open the same. There is no suggestion of an emergency release mechanism nor a frame mechanism for supporting the bucket as in the present invention and there is the necessity of the use of the additional lines to the surface in order to release the bucket. This patent does not in any way anticipate the present invention.